Generally, a large-sized motorcycle or a leisure three-wheeled vehicle that is not easy to reverse includes a reverse speed permitting reverse rotation. The reverse speed permitting reverse rotation is provided in a speed change mechanism of a power transmission system that transmits a drive from a running drive internal combustion engine to a rear wheel. Another known arrangement allows such a vehicle to be reversed on its own using a driving force of a starter motor for starting an internal combustion engine. See, for example, Japanese Patent Laid-Open No. 2001-253384. Hereinafter referred to as Patent Document 1.
Unfortunately, however, the aforementioned arrangements in the reversing apparatus suffer from numerous problems. For example, displacement in a reverse shaft by a shifter motor involves transmission loss, because rotation of the shifter motor is transmitted to rotation of a partial worm wheel via a worm. Further, the increased number of parts used contributes to a complicated structure and a need may arise for a faulty operation detection means or the like for an operation between the partial worm wheel and the worm, which could require additional space.